Magnatec 10/40 oil

[Smiley]

Advice needed.  Would Magnatec 10/40 oil be suitable for use in the 1932 RP and should the existing
oil be drained first and then start afresh.  How much oil do I need to start afresh. ?

[Reckless Rat]

Magnatec is a fully synthetic oil and whilst it is compatible with mineral oils I would drain off whatever is in the car before you use it. Be advised however that modern oils contain detergents that loosen older deposits inside the engine, which might subsequently affect engine wear. Remember there is no filtration as such in a standard engine except the sump gauze. If the inside of your engine is clean, then perhaps OK. However compared to a straight SAE30 or a 20W/50, Magnatec synthetic oil is a lot more expensive. If your engine burns oil then it's false economy. (If it's black when you take out the dip stick then it's burning oil)

Sump contains 4 pints.

[Steve kay]

Can I wholly agree with "Four Star from Frogland"  Unless the engine has just had a total rebuild, mixing synthetic or semi synthetic oil with any basic straight SAE 30 or 20/50 would be  very unwise. The detergent effect is likely to have an expensive outcome.

[Chris KC]

My personal inclination would be to hunt down some cheap 20W/50 - Halfords have normally got something for 'classic' cars. It does not need to be anything fancy.

Logically I can't see any reason whatsoever not to use a 10W/40; it's probably a better choice - I simply never have, having a lifetime's satisfactory experience of 20W/50.

With a clean engine and full-flow filter a detergent oil is no problem at all, though as Reckless counsels, on a older engine it's possible some muck may be dislodged.

[AustinWood]

Synthetic oils have much more detergent that ordinary 20/50s.

[David Stepney]

I am using Semi-synthetic 10W/40 in my RP Saloon. It is a bit thinner than a 20W/50 and i keep thinking of a thicker oil trying to get through the big end bearing jets! As Reckless Rat has said, provided the engine is clean to begin with then perhaps OK. I have had no difficulties so far, but then I have only done about 1000 miles in the car since October. Also the engine oil has been changed twice in that period, once when I got the car and again about 200 miles ago when I had the engine apart to do the rear main bearing. On both occasions, the sump and gauze was cleaned. The first time, the sump had some sludge in it and the gauze had some bits in it, but the second time, there was no 'crud' at all either in the sump of the gauze.

I note that my handbook recommends changing the oil periodically, but , frustratingly, does not specify what 'periodically' means. Something at the back of my mind says that the oil should be changed every 1000 to 1500 miles. I shall change mine at 1000 mile intervals.

[Chris KC]

A thing to keep in mind about multigrade oils is they do tend to break down slightly with prolonged use, in other words an oil which starts off as a 20W/50 may end up performing more like a straight 40 grade (in warm condition), which is about as thick as you'd want to be.

You're absolutely right to worry about thick oil struggling to get through jets and that's where the 10W is a distinct benefit - 90% of engine wear occurs at cold start.

I can't say I've ever worried that much about oil change intervals, I view it more as a constant loss system!

The strainer in the sump by the way is rudimentary at best. You may well find on inspection that the oil is able to simply flow around it! A full flow filter is a definite improvement.

[spannerman]

A filter is a must with multigrade oil as it is designed to keep the dirt in suspension so filter can remove . Straight oil drops it into.bottom of sump or oiltank as on classic bikes .

[David Stepney]

"I can't say I've ever worried that much about oil change intervals, I view it more as a constant loss system!"

Now that i have sorted out the oil leak from the tappet cover, it looks like the RP is doing circa 200/250 miles to the pint, so i can see Chris's logic.

I shall still do a proper oil change regularly, though. I can get rid of all the bits that are suspended in the oil.

[Terrytuned]

I can have used Halfords own brand 15/40 part synthetic for some yrs and at £20 for 5ltr good value. Terry.